In the semiconductor industry, there is a trend toward higher device density. In order to achieve such higher density, smaller features are required. Such requirements frequently involve scaling down device geometries to achieve lower fabrication costs, higher device integration density, higher speeds, and better performance. Along with the advantages from geometry size reductions, improvements to semiconductor devices are being made.
As semiconductor industry continues to evolve, advanced photolithography techniques have been widely used in integrated circuit fabrication operation. Photolithography operations may include techniques pertinent to coating a photoresist layer on a wafer and exposing the wafer to an exposing source.
Masks can be used in semiconductor fabrication operations to transfer a predetermined pattern onto a substrate. For example, after forming a photoresist layer over a substrate, the photoresist layer can be exposed to an actinic radiation through a mask, thus a photoresist pattern can be formed by subsequent development.
In order to improve the performance of lithography operations, a pellicle including a pellicle membrane can be used to alleviate the amount of particles fallen on patterns of the photomask. By keeping a distance between the particles and the pattern of the photomask, the particles may be out of focus under exposure operations, thereby alleviating printing defects contributed by the particles.